Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Science. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 268-286. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1979. / Microfiche copy available in Archives and Science. / Vita. / Bibliography: leaves 316-327. / by Michael Fehler. / Ph.D.

A VSP test experiment at the high temperature geothermal field Krafla in NE-Iceland has been carried out. In two boreholes a zero-, far-, and multi-offset VSP were applied to assess the applicability of VSP as a method for delineating subsurface structures like magmatic bodies, zones of supercritical fluids, superheated steam, and high permeability in volcanic geothermal fields. Because of high well temperatures (>150°C) and high attenuating surface layers, challenging field preparations were necessary. Three-component seismic data were recorded with a sufficient signal-to-noise ratio and dominant signal frequencies around 20 Hz and 40 Hz, down to 2200 m depth, for air gun and explosive sources, respectively. As a result, the data provide a good basis for several processing and imaging techniques. As part of this Master\'s thesis, standard and novel processing techniques of a subset of the data (zero and far-offset VSP in a single well) have been tested and show promising results in accordance with the lithology from well data. Besides velocity profiles and a corridor stack for both P- and S-waves were determined, a 3D Kirchhoff depth migration and Fresnel volume migration have been applied and tested. Already for a single source location, results show structures in the vicinity and below the well, and it can be assumed that further interpretation and data integration will provide a great potential in addition to hitherto applied teleseismic and potential methods. Especially, for geothermal sites it has been shown, that VSP can be applied and provide information of geometries where dipping faults and fracture zones are expected. The research leading to these results has received funding from the European Community\'s Seventh Framework Programme under grant agreement No. 608553 (Project IMAGE).

This dissertation offers an examination of the concept of sustainability, via an ethnography of geothermal life in the district of Puna on Hawaiʻi Island. In the midst of global discourse on climate change, population growth, and energy needs, ‘sustainability’ brands a remarkable number of initiatives to signify a thoughtful connection with earth, and concern with the continuation of all of existence. Close examination of what sustainable measures have meant for life in the district of Puna on Hawaiʻi Island, however, reveal the ties of discourses on and enactments of ‘sustainability’ and ‘sustainable’ living to the sustenance of market, colonial inheritance and renewability, and the manufacture of narratives that erase forms of existence—human and nonhuman, including and especially the geological. Examinations of the notion of ‘sustainability’ alongside currents of Kanaka ʻŌiwi inquiries into earth’s heat element and its relations, and settler experiences of geothermal activity, reveal the pliability of material Natures in the face of human desire, the graceless scaffolding of lives under Late Liberalism, and the structure of Late Liberal biases as suspended in love with the biontological—those forms deemed “Life.” In the dissertation I examine engagement points between literatures on Development, Indigeneity, and Space, in particular what they reveal about possible relationships with land and resource, as well as literatures on Foucauldian biopower and what Elizabeth Povinelli (2016) has termed “geontopower”—increasingly exposed arrangements of power as divisions between Life and Nonlife in the Late Liberal period—to think through the commodification of rock and earth, and the spaces between things where the possibility for hulihia (overturning) continues to exist.

Darbe projektuojama geoterminė jėgainė, kuri tiekia šiluminę energiją pastatų grupei. Darbą sudaro įvadas, keturi skyriai, išvados ir rekomendacijos bei literatūros sąrašas. Įvade pateikta nagrinėjamos temos problema, aktualumas, darbo tikslai ir uždaviniai bei praktinė darbo vertė. Pirmajame skyriuje pateikiami projektiniai duomenys pastatų grupei Tauragės miesto pavyzdžiu, aprašomi geoterminės energijos tipai bei jos panaudojimas pasaulyje ir Lietuvoje. Antrajame skyriuje analizuojamas Lietuvos geoterminis laukas bei parenkama projektuojamos geoterminės stoties vieta. Analizuojamos UAB „Geoterma“ iškilusios problemos ir nustatomos jų priežastys. Trečiajame skyriuje atliekamas metinio šilumos poreikio modeliavimas bei trijų energijos šaltinių techninis vertinimas kompiuterine programa EnergyPRO. Ketvirtajame skyriuje energijos šaltiniai vertinami ekonominiu ir aplinkosauginiu požiūriu, taip pat atliekama jautrumo analizė bei aprašomos prielaidos, naudotos darbe. Išanalizavus pastatų grupės energijos poreikius, atlikus techninius energijos šaltinių vertinimus ir reikalingus skaičiavimus šilumos gamybos galimybėms įvertinti, teikiamos išvados ir rekomendacijos. Pridedama: trijų energijos šaltinių schemos. Darbo apimtis – 65 p. be priedų, 35 pav., 15 lent., 19 literatūros šaltinių. / There is designed geothermal power plant that supplies thermal energy group of buildings in this paper. The work consists of four chapters, conclusions, recommendations and references. The introduction is about the problem of the topic, the relevance, the work goals, objectives and the practical value of the work. The first chapter provides design details of buildings group using Taurage's city example, describes the types of geothermal energy and its use in the world and in Lithuania. The second chapter analyzes the Lithuanian geothermal area, also the place for designed geothermal station is selected. Analyze the problems encountered in Geoterma company and identify their causes. There is modeling an annual heat demand and performed the three technical evaluation of energy sources with a computer program EnergyPRO. There is assessed the economic sources from energy and environmental point of view in the fourth chapter. As well sensitivity analysis is produced and description of the assumptions used in the workplace. After the analysis of the building group's energy needs and performed technical evaluations and calculations of energy sources necessary to evaluate the heat generation ability, findings and recommendations are provided. Enclosure: energy sources schemes. Working volume - 65 pages without additives, 35 pic., 15 tables, 19 references.

Thesis (Ph. D.)--University of Oregon, 1990. / Typescript (photocopy). Presented to the Department of Geological Sciences and the Graduate School of the University of Oregon in partial fulfillment of the requirements for the degree of Doctor of Philosophy. Includes bibliographical references (leaves 157-164).

The present work addresses the thermodynamic optimization of small binary-cycle geothermal power plants. The optimization process and entropy generation minimization analysis were performed to minimize the overall exergy loss of the power plant, and the irreversibilities associated with heat transfer and fluid friction caused by the system components. The effect of the geothermal resource temperature to impact on the cycle power output was studied, and it was found that the maximum cycle power output increases exponentially with the geothermal resource temperature. In addition, an optimal turbine inlet temperature was determined, and observed to increase almost linearly with the increase in the geothermal heat source. Furthermore, a coaxial geothermal heat exchanger was modeled and sized for minimum pumping power and maximum extracted heat energy. The geofluid circulation flow rate was also optimized, subject to a nearly linear increase in geothermal gradient. In both limits of the fully turbulent and laminar fully-developed flows, a nearly identical diameter ratio of the coaxial pipes was determined irrespective of the flow regime, whereas the optimal geofluid mass flow rate increased exponentially with the Reynolds number. SeveORCs were observed to yield maximum cycle power output. The addition of an IHE and/or an Oral organic Rankine Cycles were also considered as part of the study. The basic types of the FOH improved significantly the effectiveness of the conversion of the available geothermal energy into useful work, and increased the thermal efficiency of the geothermal power plant. Therefore, the regenerative ORCs were preferred for high-grade geothermal heat. In addition, a performance analysis of several organic fluids was conducted under saturation temperature and subcritical pressure operating conditions of the turbine. Organic fluids with higher boiling point temperature, such as n-pentane, were recommended for the basic type of ORCs, whereas those with lower vapour specific heat capacity, such as butane, were more suitable for the regenerative ORCs. / Dissertation (MEng)--University of Pretoria, 2013. / Mechanical and Aeronautical Engineering / unrestricted

This research describes the development and application of a numerical modelling method for angled borehole heat exchangers in ground-source heat pump systems. Inclining the boreholes relative to the vertical axis presents an opportunity to reduce the ground level footprint of the borehole field thus allowing for the installation of geothermal systems in retrofit applications or under buildings with small footprints. The commercial code COMSOL was used to develop the computational model. A series of validation and verification studies were performed to ensure the accuracy of the modelling approach. Simulations were conducted under constant and transient heat injection, where the effect of energy load imbalance is analyzed. Additionally, the effect of discontinuous loading with natural and forced recovery cycles is investigated. When exposed to a constant heat injection rate, configurations of angled borehole heat exchangers initially perform the same as vertical borehole heat exchangers. Then, there is a relatively short period where the angled configurations have slightly decreased performance due to increased thermal interaction in the near surface. At longer times, however, there is a significant benefit in using angled borehole heat exchangers as a result of the increased ground volume in the lower portion of the field. Under transient loading conditions, the conclusions were the same as constant heat injection, although the differences were smaller when the energy loading was balanced. However, when the loading was cooling dominated, by year 10 there was a significantly better performance observed for the angled boreholes. This indicates that the configurations of angled borehole heat exchangers can withstand a higher intensity of imbalanced energy loads compared to vertical configurations. Discontinuous loading was investigated by varying the length of time heat injection would occur on a daily basis. These daily perturbations led to small performance losses in the angled boreholes due to the increased thermal interaction in the near surface. Furthermore, imposing a forced recovery on the system by circulating fluid while heat injection was off did not significantly affect the fluid temperature or ground temperature. / Thesis / Master of Applied Science (MASc)

Cette thèse de doctorat a pour objet l'étude d'échangeurs géothermiques hélicoïdaux implantés dans le proche sous-sol. Ces objets font partie de la famille des échangeurs géothermiques compacts, et sont une alternative aux sondes verticales et aux nappes horizontales plus couramment utilisées pour chauffer et rafraîchir des bâtiments (géothermie sèche, très basse enthalpie). L'étude à la fois théorique et expérimentale de ces échangeurs mène à différents modèles, numériques comme analytiques, permettant de prévoir le comportement en température du sous-sol comme du fluide caloporteur. Des résultats de simulation intégrant le couplage aux bâtiments sont présentés, et des outils logiciels ont été créés pour aider au dimensionnement d'installations. De surcroît, un "test de réponse thermique" adapté à ces échangeurs a été développé, afin de permettre d'estimer les propriétés thermiques moyennes du sous-sol et la résistance thermique liée à l'installation de l'échangeur. Enfin, des conseils pratiques sont donnés, dont le but est d'obtenir les températures d'utilisation les mieux adaptées aux pompes à chaleur, et en conséquence d'améliorer les coefficients de performance du système. / This thesis consists in a study of geothermal helical heat exchangers buried in the close underground. These objects belong to the compact exchangers kind and may be used instead of borehole heat exchanger or geothermal horizontal exchangers to cope with the needs in heating and cooling buildings with a heat pump. A theoretical and experimental study of these exchangers leads to numerical and analytical models which can be used to estimate the temperatures in the underground and in the exchanger over years. Results of simulations including a building are given, and softwares were developed to help with the sizing of installations. Moreover, a specific "thermal response test" for helical heat exchangers was developed, in order to estimate the mean thermal properties of the underground and the thermal resistance between the heat transfer fluid and the underground. At least, practical advices are given, which goal is to get more valuable temperatures at the heat pump and as a consequence better coefficients of performance of the geothermal system.

The purpose of this study is to examine the geothermal potential, sustainability, and reinjection possibility of Edremit geothermal field. In order to investigate this, a numerical model consisting of a hot and cold water aquifer system is established. A two dimensional cross sectional model is set to simulate this geothermal system. Different pressure and temperature values are applied to the nodes at the boundaries to perform a steady state calibration which minimizes the computed results and observed values obtained from the near well logs. After the calibration, three alternative scenarios are proposed and the response of the pressure and temperature to these conditions is evaluated. At first the water is pumped from the wells of Yagci, Derman, Entur and ED-3 seperately at a mass rate of 5 kg/s and energy rate of 4.182 x 105 J/s. Then, in scenario 2 the water is pumped at the same rate from all the wells mentioned in the first scenario together. For the third scenario another well is opened to the geothermal system and 80% of the pumped water (temperature being 200C) is injected to the system from the wells while all the wells mentioned are working. The results of these scenarios are utilized to evaluate the reservoir in terms of its response to different production and reinjection conditions. Interpretation of the reservoir response in view of the pressure and temperature declines emphasize that such a simulation study can be applied to assess potential and sustainability of the geothermal systems.